CVE-2025-9515 is a high-severity vulnerability affecting the Multi Step Form plugin for WordPress, developed by mondula2016. This vulnerability arises from the plugin's import functionality, which lacks proper file type validation, thereby allowing authenticated users with Administrator-level privileges or higher to upload arbitrary files to the web server. The core issue is categorized under CWE-434: Unrestricted Upload of File with Dangerous Type. Because the plugin fails to restrict or validate the types of files uploaded, attackers can upload malicious files such as web shells or scripts that could be executed remotely, potentially leading to remote code execution (RCE). The vulnerability affects all versions of the plugin up to and including version 1.7.25. The CVSS v3.1 base score is 7.2, indicating a high severity level, with the vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H. This means the attack can be performed remotely over the network with low attack complexity but requires high privileges (Administrator or above) and no user interaction. The impact on confidentiality, integrity, and availability is high, as successful exploitation could allow full control over the affected WordPress site and potentially the underlying server. No known exploits are currently reported in the wild, and no patches have been linked yet, indicating that mitigation may require manual intervention or monitoring for updates from the vendor. Given that WordPress is a widely used CMS in Europe and the plugin is used to create multi-step forms, this vulnerability presents a significant risk for websites relying on this plugin, especially those with multiple administrators or where privilege escalation is possible.

For European organizations, the impact of this vulnerability can be substantial. Many European businesses, government agencies, and non-profits use WordPress as their content management system, often relying on plugins like Multi Step Form for customer interactions, surveys, or data collection. An attacker exploiting this vulnerability could upload malicious files leading to remote code execution, which may result in data breaches, defacement of websites, disruption of services, or use of the compromised server as a pivot point for further attacks within the organization's network. The requirement for administrator-level access limits the attack surface but does not eliminate risk, especially in environments where administrator credentials may be compromised or insider threats exist. Additionally, the GDPR framework in Europe imposes strict data protection and breach notification requirements, so exploitation could lead to regulatory penalties and reputational damage. The absence of known exploits in the wild currently provides a window for proactive mitigation, but the high severity score underscores the urgency of addressing this vulnerability promptly.

1. Immediate mitigation should include restricting administrator access to trusted personnel only and enforcing strong authentication mechanisms such as multi-factor authentication (MFA) to reduce the risk of credential compromise. 2. Monitor and audit administrator activities and file uploads closely to detect any anomalous behavior indicative of exploitation attempts. 3. Disable or remove the Multi Step Form plugin if it is not essential to reduce the attack surface until a patch is available. 4. If the plugin is critical, implement web application firewall (WAF) rules to block or inspect file uploads to the import functionality, focusing on detecting and preventing uploads of executable or script files. 5. Regularly check for updates from the plugin vendor and apply patches as soon as they are released. 6. Conduct internal security reviews and penetration testing focusing on privilege escalation and file upload mechanisms within WordPress environments. 7. Employ file integrity monitoring on web server directories to detect unauthorized file uploads or modifications. 8. Educate administrators on the risks of this vulnerability and best practices for secure plugin management and credential handling.